It is known that corrosion imposes havoc on the grooved pipe industry. Grooved pipe technology is a method by which pipes and associated components are joined together through a clamp or a coupling. In such configurations, the ends of the pipes to be joined and associated components have grooved interfaces that allow the clamp or coupling to hold adjacent components together. The clamp or coupling is also provided with a rubber gasket or seal in order to seal the joint between the pipes.
Grooved pipe components were developed during the First World War as a mean to quickly deliver fuel and water supplies to Allied forces. Following the war, this efficient method of joining pipes was adapted for everyday use in modern society. Given their ease of use and adaptable characteristics, grooved pipes have developed into a very important industry in North America, as well as in other regions.
Several different types of suppliers, distributors and manufacturers are currently involved in the production and distribution of grooved pipes and their associated products, which are used in industries of various types. As an example, grooved pipes are used for, but not limited to, the mining industry, the pulp and paper industry, the oil and gas industry, the power generation industry, institutional facilities and many other industries requiring fluid handling applications.
In terms of applications, grooved pipes are usually used for, but not limited to, heating, ventilation and air conditioning (HVAC), fire Suppression Systems, water distribution, waste removal and oil field operations.
As will be detailed below, in certain circumstances, the lifespan of grooved pipes can be greatly enhanced by the combination of such pipes with a sacrificial anode system.
A sacrificial anode or sacrificial rod is a metallic anode used in cathodic protection, where it is intended to be dissolved to protect other metal components. The main idea is that the more active metal (i.e. the anode) oxidized more easily than the protected metal (i.e. the cathode) and corrodes first, hence the term sacrificial. Generally, the anode oxidizes nearly completely before the less active metal will corrode, therefore acting as a barrier against corrosion for the protected metal.
As shown in FIG. 1, when the sacrificial anode 16 is attached to a metal structure 11 to be protected, and the two are submersed in water or buried in the earth 50, an electrochemical cell is created. The earth or the water provides the ionic pathway necessary for cathodic protection to take place. Therefore, simply bolting a piece of active metal such as zinc to a less active metal, such as mild steel, and leaving it in the open air does not provide any protection, in the absence of the ionic pathway essential to cathodic protection.
Sacrificial anodes were discovered in the 1800s and have evolved a great deal since then. They are currently most commonly used, but are not limited to, the protection of underground water pipe lines, underground fuel pipe lines, underground storage tanks, steel pier piles, ship hulls (for both salted and fresh water), offshore oil platforms and outboard marine engines (for both salted and fresh water).
In the absence of the cathodic protection provided by the sacrificial anodes, the corrosion rate of the above mentioned structures would greatly increase. Consequently, the overall cost associated with the corrosion of the structures for individuals, businesses and government would be devastating. For example, without sacrificial anodes, water mains would never last the 30 plus years they are currently expected to.
Once an anode has expired, it usually can simply be replaced with a new one (i.e. once the anode is corroded away, it can be replaced with an uncorroded one). Anodes come in all shapes and sizes and are typically alloys of zinc, magnesium and aluminum.
It is important to bear in mind that for a sacrificial anode to work, both the structure and the anode must simultaneously be buried into the earth or submersed in water. It is the earth or the water that provides the ionic pathway to complete the electrochemical cell necessary for cathodic protection. Therefore, attaching an anode to a non submersed or buried pipe would provide no protection whatsoever.
Consequently, there is still presently a need for a sacrificial anode system that can be used in a non-submersed or non-buried pipe.